Picowatt-Power Super-Cutoff Analog Building Blocks and 78-pW Battery-Less Wake-Up Receiver for Light-Harvested Near-Always-On Operation

Techniques to reduce power well below regular transistor leakage in analog circuits are introduced. Key building blocks with super-cutoff transistor operation (i.e., V_{\mathrm {GS}} < 0 V) and pW-range consumption are demonstrated. Single-ended and fully differential versions of operational transconductance amplifiers (OTAs) are presented in several configurations, achieving 37-dB dc gain, 22.4-Hz gain-bandwidth product, and 25- \mu \text{V} input-referred noise at 6.87 pW in 180-nm CMOS. For system-level demonstration, the proposed techniques are used in an optical wake-up receiver (WuRx) for light fidelity (LiFi) applications with 78-pW power. Continuous operation with a near-100% uptime is demonstrated when solely powered by an unregulated 1-mm2 solar cell down to 1 lx (moonlight) with no energy storage.